I go to turn on my TS over the weekend and all I get is a humming sound from the motor, but no motion to the blade–although the blade sort of twitched a little.
There was no burning smell or smoke just the electrical hum and then the 20 amp breaker trips.
It really sounded like it wants to start up but it just can’t get enough power to start up.
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It is a Craftsman from Sears. The motor power cable actually plugs into the back of the on/off switch box–and there is power coming out of the starter box–is it possible that if the switch is bad it could be causing the amps? voltage to drop? I checked that power was getting to that socket on the back of the on/off switch but not with volt meter just one of thoses cheap socket testers. |
It is getting electricity and none of the other tools are having any problems.
Is my motor dead or is there another explanantion.
Any advice would be greatly appreciated. Thank You
cje
Replies
I'll take a stab and say that it sounds like your cap on your motor went tits up. Or maybe a centrifugal switch in the motor for cutting in/out the cap, though I doubt it's that complicated a setup. Basically the capacitor helps create the phase shift necessary to simulate relative motion btwn rotating magnetic fields that actually pushes the motor along. Once the motor gets going, the cap isn't really necessary, so some setups have a centrifugal switch to cut it out at a certain percentage of rated speed. Like I said, I kind of doubt a table saw motor would have such a switch.
If it were *me*, I would consider getting a stick of scrap a couple feet long, stand off to one side behind the saw, i.e. on the motor side, after everything is reset, start the saw and then gently push the blade in the normal direction of rotation w/ the piece of scrap. Odds are if the cap is the only thing bad, the motor will take off running once you spin it a little.
In any case, I'd say get the motor unwired and take it to a local motor repair/rewind shop for an analysis. Most of them around here will do free 'bench-testing' of motors, alternators, etc. i.e. you bring it in to them and they will hook it up and test it. If they have to come out and test it, unwire it, whatever, they charge a diagnostic/troubleshooting fee. Not sure what to expect as far as a replacement cost. Most of the stuff I messed w/ were larger industrial motors where the capacitors were designed to be serviceable instead of replacing the motor whole.
Anywho, hopefully this helps a bit.
Monte
Before you do anything else, try cleaning out the motor and switch with compressed air and/or a shop vac. In fact, get the whole inside of the cabinet cleaned up real nice. Often that'll do the trick.
My portable table saw does the same thing once or twice a year. I think its because the arbor stops at exactly a certain point that the capacitor can't get it going. Mine just needs a little push.
My craftsman did the same thing. The shaft bushings got gummed up. Take apart motor,4 bolts. Clean and shine with fine emery,oil and reinstall.
larry
Throw away the "crapsman" & buy a better quality tablesaw. DeWalt portable is the best out there.
This is real easy. the weights on the motor shaft have moved. Unplug and then through the vent holes push the weights back towards the center of the motor. Plug in and carry on cutting. If they keep moving, place a wrap of electrical tape on the end of the shaft. This exact thing happens on the rad.arm saw from sears.
Well I took the motor off last night and fiddled with this and faddled with that and didn't really do anything other than take out bolts and then put them back in blew out some saw dust, pounded on it a bit and...now it works just fine ..at least for now.
so thanks
cjeTake what you want, leave the rest
cjeden,
On the side of the motor on your saw on the plastic part there should be some thing that looks like a big flat head screw, take this out and inspect it that is the brushes that go to the motor and there should be one on each side of the motor.Now if the brushes are concave in the middle then your brushes are to worn an you need to replace them however, if it is still flat at the bottom it should be ok. i had the same problem with my delta sawbuck and all i did was change the brushes and it was like new all over agian.Hope that helps ya !!!!
Good Luck!
Shavey
Universal motors use brushes and if the brush is "bad" so that there is no connection then the motor will not hum.
Now there are a few other types of AC motors that uses brushes such as repulsion-induction, but they are very rare and old design.
His symptoms (motor hums, but won't run) are classic symptoms of an single phase induction motor with a bad start circuit. It can be bad because of the certrifical start switch, bad cap, or burnt out start winding.
Almost all stationary power tools (table saws, compressors, bandsaws, etc) use capacitor start induction motors.
Universal motors are used on power hand tools, such as drills, and smaller power tools such as job site table saws.